This invention relates to a slicing apparatus used for cutting a work such as a block of semiconductor material into slices, and, in particular, relates to a slicing apparatus in which a work is moved relative to a blade at a constant cutting speed so as to regulate the cutting force, thereby being cut into slices of an excellent quality.
A known slicing apparatus of the aforementioned type includes: an inside diameter rotary blade of an annular plate-like configuration having an inner peripheral cutting edge and adapted to be rotated at a high speed; a table for carrying a work to be cut; a first work-feeding mechanism for moving the work on the table in a first direction parallel to the axis of the rotary blade to confront the work on the table with the inner peripheral edge of the rotary blade; and a second work-feeding mechanism for moving the table in a second direction parallel to the opposite sides of the blade in order to have the work on the table sliced by the blade.
In the slicing apparatus described above, the second work-feeding mechanism includes a hydraulic cylinder in open loop control. This is because the movement in the second direction of the table is so simple that it is thought not to be necessary to control the travel speed or cutting speed of the table with high accuracy.
However, when a work is sliced by using this slicing apparatus, there arises such a problem that the blade vibrates during the slicing apparatus, and thereby not only the work but also the blade tend to be damaged. The inventors analyzed the cause of the vibration, and have discovered that the blade vibrates because the cutting speed is varied during the cutting operation. The rotary blade is usually set on the apparatus with its sides warped or curved at a predetermined degree to restrain it from vibration. However, this degree of the warp or curvature is varied during the cutting operation when the cutting force varies. This variation in the cutting force is caused by the variation in the cutting speed. Consequently, when the cutting speed varies during the operation, the blade begins to vibrate, resulting in the damage of the blade and the resultant slices of the work. The inventors have also discovered the following reasons for the variation of the cutting speed.
The cutting speed is varied because of:
(1) the abrasion of parts of the slicing apparatus, such as bearings which support the spindle of the blade;
(2) the secular change of viscosity and compressibility of the pressure oil of the hydraulic cylinder; and
(3) the variation of an area of the blade's sides in contact with the work during the cutting operation.
The present invention has been made with the background mentioned above.